Portable structure having sufficient internal structural rigidity to eliminate load-bearing perimeter support structures

ABSTRACT

A mobile structure includes first and second rigid frames and first and second horizontal roof supports supported by the rigid frame. Each of the rigid frames includes a first vertical support, a second vertical support substantially parallel to the first vertical support, and a lateral rigid frame support extending perpendicularly at least from the first vertical support to the second vertical support. The mobile structure further includes a floor under the first and second horizontal roof supports, a wheel-axle assembly under the floor, and leveling assemblies that are extendable away from the floor. Each leveling assembly is in weight-bearing and in-line relationship with respect to one of the vertical supports of the first rigid frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to U.S.patent application Ser. No. 12/845,062, entitled “A MOBILE STRUCTUREHAVING SUFFICIENT INTERNAL STRUCTURAL RIGIDITY TO ELIMINATE NEED FORLOAD-BEARING PERIMETER SUPPORT STRUCTURES,” filed Jul. 28, 2010, whichapplication is fully incorporated herein in its entirety by thisreference, and which claims the benefit of and priority to U.S.Provisional Patent Application No. 61/271,925, entitled “SUSTAINABLE,MOBILE, EXPANDABLE STRUCTURE,” filed Jul. 28, 2009, which application isfully incorporated herein in its entirety by this reference.

FIELD OF THE INVENTION

The present invention generally relates to mobile structures, and moreparticularly to towable mobile structures having substantial living,working, and/or storage space.

BACKGROUND OF THE INVENTION

As used in this application, the term “mobile structure” is intended toencompass any structure, including a living, working, or storage area,that is mobile, i.e., capable of being pulled or towed (e.g., with ahitch). Thus, a “mobile structure,” as the term is used herein, includestrailers, campers, recreational vehicles, mobile laboratories, andmobile medical units, among other things.

Mobile structures are typically inferior to more permanent structures.For example, mobile structures typically have less structural stability,fewer floor plan options, and smaller interior space.

To increase the usable interior space, some mobile structures expandwhen they arrive at their destination. For example, some mobilestructures include pop-out rooms or slide-out rooms. However, the size,stability, and accessibility of such pop-out rooms and slide-out roomsis limited.

SUMMARY OF THE INVENTION

In mobile structure embodiments of the present invention a uniqueconfiguration of structural framing elements, including rigid frames andleveling assemblies provide, among other things, flexibility in floorplan options, ease of use, and structural stability while minimizing anamount of material used and accommodating expansions areas.

A first general aspect of the invention is a mobile structure with ampleinterior space unobstructed by structural members. The mobile structureincludes: first and second rigid frames, each of the first and secondrigid frames including: a first vertical support; a second verticalsupport substantially parallel to the first vertical support; and alateral support extending perpendicularly at least from the firstvertical support to the second vertical support; first and secondhorizontal roof supports, the first and second horizontal roof supportsbeing supported by the first and second rigid frames, and being mutuallyparallel; a floor under the first and second horizontal roof supports; awheel-axle assembly under the floor; and a first set of levelingassemblies that are extendable down from the floor, each levelingassembly being in weight-bearing and in-line relationship with respectto one of the vertical supports of the first rigid frame.

In a preferred embodiment, the leveling assemblies are extendable tosupport the mobile structure on a surface when the mobile structure isin a stationary mode, and are retractable from their extendedconfiguration when the mobile structure is in a transport mode.

In another preferred embodiment, the first rigid frame further includesa lateral floor joist that is substantially parallel to the lateralsupport, and that extends at least from the first vertical support tothe second vertical support.

In another preferred embodiment, the mobile structure further includes ahitch in towing relationship with the floor.

In a further preferred embodiment, the mobile structure further includesa hitch leveling assembly extendable down from the hitch.

In yet another preferred embodiment, the mobile structure furtherincludes at least one vertical roof support extending up from the floorto support one of the horizontal roof supports.

In another preferred embodiment, the mobile structure further includes asecond set of leveling assemblies that are extendable down from thefloor, each leveling assembly of the second set of leveling assembliesbeing in weight-bearing and in-line relationship with respect to one ofthe vertical supports of the second rigid frame.

In another preferred embodiment, the mobile structure includes a firststabilizing frame disposed outside of a space between the first andsecond rigid frames, the first stabilizing frame supporting andlongitudinally stabilizing the first and second horizontal roofsupports, the first stabilizing frame having a first vertical roofsupport and a second vertical roof support substantially parallel to thefirst vertical roof support, and the first and second vertical roofsupports being supported by the floor.

In a further preferred embodiment, the mobile structure includes asecond stabilizing frame disposed outside of a space between the firstand second rigid frames, and disposed in symmetric relationship withrespect to the first stabilizing frame, the second stabilizing framesupporting and longitudinally stabilizing the first and secondhorizontal roof supports, the second stabilizing frame having a firstvertical roof support and a second vertical roof support substantiallyparallel to the first vertical roof support, and the first and secondvertical roof supports of the second stabilizing frame being supportedby the floor.

In yet another preferred embodiment, the mobile structure furtherincludes: an eave support assembly supported by the first and secondhorizontal roof supports, the eave support assembly including: a firstlongitudinal eave support; a second longitudinal eave supportsubstantially parallel to the first longitudinal eave support; and aplurality of lateral eave supports each extending perpendicularly atleast from the first longitudinal eave support to the secondlongitudinal eave support, the first and second longitudinal eavesupports being separated from one another by a distance greater than adistance separating the first and second vertical supports of at leastone of the first and second rigid frames.

In a further preferred embodiment, each of the first and secondhorizontal roof supports includes a truss, the truss including a bottomchord joined to the first and second rigid frames; a top chord disposedabove and in parallel with the bottom chord, the top chord being joinedto the eave support assembly; and truss members disposed in triangularpatterns between the top and bottom truss chords.

In yet another preferred embodiment, an extension distance of at leastone of the leveling assemblies of the first set of leveling assembliesis manually adjustable.

In yet another preferred embodiment, an extension distance of at leastone of the leveling assemblies of the first set of leveling assembliesis automatically adjustable.

In another preferred embodiment, at least one of the leveling assembliesof the first set of leveling assemblies includes a base plate so as todistribute a load of the mobile structure over an area under the baseplate.

In another preferred embodiment, each of the vertical supports of thefirst rigid frame extends through the floor and is joined in aweight-bearing and in-line relationship to a corresponding one of theleveling assemblies of the first set of leveling assemblies.

A second general aspect of the invention is a mobile structure withample interior space unobstructed by structural members. The mobilestructure includes: first and second rigid frames each including: afirst vertical support; a second vertical support substantially parallelto the first vertical support; and a lateral rigid frame supportextending at least from the first vertical support to the secondvertical support. The mobile structure further includes: first andsecond horizontal roof supports, the first and second horizontal roofsupports being supported by the first and second rigid frames, and beingmutually parallel; a floor under the first and second horizontal roofsupports, each of the vertical supports of the rigid frames extendingthrough the floor; a wheel-axle assembly disposed under the floor;leveling assemblies that are extendable down from the floor, eachleveling assembly being in weight-bearing and in-line relationship withrespect to one of the vertical supports of the first and second rigidframes; a hitch in towing relationship with the floor; and an eavesupport assembly disposed above and supported by the first and secondhorizontal roof supports. The eave support assembly includes: a firstlongitudinal eave support; a second longitudinal eave supportsubstantially parallel to the first longitudinal eave support; and aplurality of lateral eave supports each extending perpendicularly atleast from the first longitudinal eave support to the secondlongitudinal eave support, the first and second longitudinal eavesupports being separated from one another by a distance greater than adistance separating the first and second vertical supports of at leastone of the first and second rigid frames.

In a preferred embodiment, the mobile structure includes: a firststabilizing frame disposed outside of a space between the first andsecond rigid frames, the first stabilizing frame supporting andlongitudinally stabilizing the first and second horizontal roofsupports, the first stabilizing frame having a first vertical roofsupport and a second vertical roof support substantially parallel to thefirst vertical roof support, and the first and second vertical roofsupports being supported by the floor.

In another preferred embodiment, the mobile structure further includes:a second stabilizing frame disposed outside of a space between the firstand second rigid frames, and disposed in symmetric relationship withrespect to the first stabilizing frame, the second stabilizing framesupporting and longitudinally stabilizing the first and secondhorizontal roof supports, the second stabilizing frame having a firstvertical roof support and a second vertical roof support substantiallyparallel to the first vertical roof support, and the first and secondvertical roof supports of the second stabilizing frame being supportedby the floor.

In another preferred embodiment, each of the first and second horizontalroof supports including a truss, the truss comprising: a bottom chordjoined to the first and second rigid frames; a top chord disposed aboveand in parallel with the bottom chord, the top chord being joined to theeave support assembly; and truss members disposed in triangular patternsbetween the top and bottom truss chords.

In a further preferred embodiment, at least one of the first and secondrigid frames further includes a lateral floor joist that issubstantially parallel to the lateral support, and that extends at leastfrom the first vertical support to the second vertical support.

Additional features of the invention will be set forth in thedescription which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures of the invention may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. These and other features of the present invention will becomemore fully apparent from the following description and appended claims,or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description can be better understood in light of Figures,in which:

FIG. 1 is a perspective view of structural framing elements in anexample embodiment of a mobile structure;

FIG. 2 is a perspective view of the mobile structure of FIG. 1 and showsadditional structural framing elements; and

FIG. 3 is a cross-section perspective view of the mobile structure ofFIG. 2.

DETAILED DESCRIPTION

Reference will now be made to the figures wherein like structures willbe provided with like reference designations. It is understood that thefigures are diagrammatic and schematic representations of presentlypreferred embodiments of the invention, and are not limiting of thepresent invention, nor are they necessarily drawn to scale.

Embodiments of mobile structures described herein may provide, amongother things, structural elements that provide rigidity and stabilityunder heavy loads while enabling reconfiguration of the mobile structureinto different modes of operation and permitting flexible floor planoptions. Among the various structural elements is a plurality of rigidframes that use a minimal amount of material and preserve an openinterior space while enhancing structural stability by effectivelytransferring lateral forces to leveling assemblies located directlyunder and in-line with vertical supports of the rigid frames. An eavesupport assembly also enhances structural stability by transferringinternal and external loads to the rigid frames.

FIGS. 1 and 2 show a perspective view of structural framing elements ofan example embodiment 100 of a mobile structure. As depicted in FIG. 1,mobile structure 100 comprises various structural framing elementsincluding, for example, a carriage assembly 102, rigid frames 104,stabilizing frames 106, primary leveling assemblies 112, and a secondaryor hitch leveling assembly 114. FIG. 2 additionally shows horizontalroof supports 108 and an eave support assembly 110. Each of theforegoing elements and their relationship to one another are describedbelow.

Mobile structure 100 is a lightweight structure capable of beingconveniently airlifted, towed, and/or hauled to any desired location.Carriage assembly 102 provides means for mobile structure 100 to beconveniently towed with the aid of a motive force, such as a truck, andprovides a base on which a working/living space of mobile structure 100rests. Carriage assembly 102 includes a floor diaphragm (also referredto as “floor”) 102 a mounted to a plurality of transverse joists 102 c(hidden from view by floor diaphragm 102 a), which are in turn mountedto and disposed perpendicular to peripheral carriage longitudinalchannels or beams 102 b.

Carriage assembly 102 further includes a hitch 102 d, angled neck beams102 e joined to carriage longitudinal beams 102 b and meeting at hitch102 d, a wheel-axle assembly 102 f mounted on an underside of floordiaphragm 102 a, and a fender 102 g mounted over wheels of wheel-axleassembly 102 f. Wheel-axle assembly 102 f may be mounted to longitudinalbeams (depicted in FIG. 3 as carriage longitudinal beams 102 j underfloor diaphragm 102 a) via a leaf spring suspension 102 h. Floordiaphragm 102 a may include or be joined to a tongue 102 i coextensivetherewith and extending outwardly toward hitch 102 d.

Moreover, although wheel-axle assembly 102 f is depicted as having twoaxles and four wheels, one of ordinary skill will appreciate that adifferent number of wheels and/or a different number of axles (e.g., oneaxle and a corresponding pair of two wheels) may be used as differentwheel-axle assemblies' weight limits will permit. Moreover, althoughcarriage assembly 102 is described as including various pieces or parts,a group of some or all of the parts may be formed as one integral piece.Conversely, one or more of the carriage assembly parts may be comprisedof various sub-parts. Materials used to make the various parts ofcarriage assembly 102 may include any suitable materials including, forexample, wood, metal (e.g., aluminum, steel), plastic, etc. and jointsbetween parts may be of a type that is suitable for the material usedincluding, for example, mortise and tenon joints or welded joints, etc.Fasteners for the joints may include bolts, nails, screws, rivets,adhesives, etc., as appropriate for the joint type.

Rigid frames 104 and stabilizing frames 106 are joined to and extendupward from carriage assembly 102 to support eave support assembly 110.Rigid frames 104 also bear lateral loads from wind or other externalforces, transferring such forces to the ground via primary levelingassemblies 112. Although two rigid frames 104 are depicted, additionalrigid frames may be included for increased support, particularly forembodiments of mobile structure 100 having relatively larger dimensions.

Rigid frames 104 include a rear rigid frame 104-1 proximate a rear endof mobile structure 100 and a front rigid frame 104-2 proximate a frontend of mobile structure 100. Each of rigid frames 104 includes a lateralfloor joist 104 a (visible in FIG. 3), a pair of vertical supports 104 bthat run parallel to each other, and a lateral support 104 c. Allconnections between components of rigid frames 104 are rigidconnections, such as welded or bolted connections. By way of example andnot limitation, vertical supports 104 b may be separated from each otherby a distance of about three to about five feet. Lateral support 104 cand lateral floor beam 104 a of each rigid frame extends at least fromone vertical support 104 b of the rigid frame to the other verticalsupport 104 b of the rigid frame and, optionally, beyond the verticalsupports.

Stabilizing frames 106 include a rear stabilizing frame 106-1 proximatea rear end of mobile structure 100 and a front stabilizing frame 106-2proximate a front end of mobile structure 100. Each of stabilizingframes 106 supports and longitudinally stabilizes the first and secondhorizontal roof supports 108, among other things. Each of stabilizingframes 106 also includes a lateral floor joist 106 a (not shown, butsimilar in position to later floor joists 104 a depicted in FIG. 3 ofrigid frames 104) and a pair of vertical roof supports 106 b that runparallel to each other. Moreover, each of stabilizing frames 106includes lateral supports 106 c and 106 d extending at least from onevertical roof support to the other vertical roof support of thestabilizing frame. All connections between components of stabilizingframes 106 are rigid connections, such as welded or bolted connections.

Rigid frames 104 are disposed centrally over carriage assembly 102 withrespect to the more outwardly disposed stabilizing frames 106. Moreover,stabilizing frames 106 are disposed outside of a space between the firstand second rigid frames, and in symmetric relationship with respect toeach other. Thus, front stabilizing frame 106-2 and rear rigid frame104-1 are disposed on opposite sides of and longitudinally in line withfront rigid frame 104-2. Similarly, rear stabilizing frame 106-1 andfront rigid frame 104-2 are disposed on opposite sides of andlongitudinally in line with rear rigid frame 104-1. By way of exampleand not limitation, front and rear rigid frames 104 are spaced apart bya distance of about eight to about sixteen feet, to allow for flexiblefloor plan options and convenient passage to lateral extension areasthat may be deployed in a stationary mode of mobile structure 100. Adistance between rear stabilizing frame 106-1 and rear rigid frame104-1, on the other hand, may be smaller, e.g., between about three andabout eight feet but not limited to this range of dimensions. A distancebetween front stabilizing frame 106-2 and front rigid frame 104-2 mayalso be of the same or a similar distance (i.e., between about three andabout eight feet but not limited to this range of dimensions).

Rigid frames 104 may include or may be joined directly to primaryleveling assemblies 112. For example, in one embodiment, verticalsupports 104 b of each rigid frame extend through floor diaphragm 102 aof carriage assembly 102 and integrally include primary levelingassemblies 112. Alternatively, each vertical support 104 b may besleeved within an upper component of a corresponding primary levelingassembly 112 to a depth of about four to eight inches (but not limitedto this range). Vertical supports 104 b may be welded and or bolted toprimary leveling assemblies 112 in the sleeved configuration.

In another embodiment, primary leveling assemblies 112 are not joineddirectly to or integrally part of vertical supports 104 b but each isinstead mounted to a beam or support on an underside of floor diaphragm102 a in weight-bearing and in-line relationship with a correspondingone of vertical supports 104 b. In either embodiment, however, a loadtransferring effect is similar-loads bearing on vertical supports 104 bof each rigid frame are transferred to the ground via primary levelingassemblies 112 without introducing extraneous torsion on any beams orsupports of carriage assembly 102.

Primary leveling assemblies 112 are extendable away from the undersideof floor diaphragm 102 a when configuring mobile structure 100 in itsstationary mode. Primary leveling assemblies 112 may be extended longenough to raise the wheels of mobile structure 100 off the ground or sothe wheels just touch the ground or in some instances the wheels may addsubstantial support to the structure. An amount of extension iscontinuously or discretely variable to accommodate grade elevationvariations of a surface on which mobile structure 100 is deployed.Moreover, primary leveling assemblies 112 may include jacks that aremanually or automatically extendable and base plates or pads at distalends thereof to distribute a load of the mobile structure over an areaunder the base plate. Secondary leveling assembly 114, located proximatehitch 102 d, is similar in function to primary leveling assemblies 112,but will typically not need to bear as much weight and may thereforehave a lower weight limit rating than primary leveling assemblies 112.

As depicted in FIG. 2, horizontal roof supports 108 are disposed abovefloor diaphragm 102 a and are joined to rigid frames 104 in aperpendicular relationship with respect to vertical supports 104 b andlateral supports/beams 104 a/104 c of each rigid frame. Horizontal roofsupports 108 may include web tension and compression members 108 a (alsocalled truss members) and top and bottom chords 108 b. As depicted, webtension and compression members 108 a are disposed in triangularpatterns. Horizontal roof supports 108 are joined (e.g., by bolting orwelding) to rigid frames 104 at the intersection of vertical supports104 b and lateral supports 104 c.

Horizontal roof supports 108 stabilize the position of each rigid frame104 with respect to each another and transfer uplift or compressionforces generated by lateral loads into vertical supports 104 b. Thus,horizontal roof supports 108 provide rigidity to the overall frame ofmobile structure 100. For example, without horizontal roof supports 108rigid frames 104, when subjected to sufficiently strong forces, couldbuckle or fold. Moreover, distal ends of horizontal roof supports 108are restrained by vertical roof supports 106 b of stabilizing frames 106to resist external lateral forces in addition to gravity loads.Furthermore, by locating horizontal roof supports 108 in an overheadassembly instead of in walls of mobile structure 100 or some other areathat limits floor plan flexibility, open passages are preserved on thesides of mobile structure 100 for use with lateral extension areas.

As further depicted in FIG. 2, eave support assembly 110 positioned andsupported above horizontal roof supports 108 includes lateral eavesupports 110 a, longitudinal stiffeners 110 b, longitudinal eavesupports 110 c, and a roof diaphragm 110 f. Eave support assembly 110provides a base roof structure that is used to transfer roof diaphragmloads to horizontal roof supports 108 and to rigid frames 104 and 106whether or not additional roof framing, such as sloped rafters, areutilized.

Lateral eave supports 110 b are arranged in a parallel relationship andare rigidly joined to horizontal roof supports 108. Longitudinalstiffeners 110 b are also arranged in a parallel relationship withrespect to each other, but perpendicular to lateral eave supports 110 ato provide overturning stability to lateral eave supports 110 a.

An on center spacing of lateral eave supports 110 a may be, but is notlimited to, a dimension of about two feet to about six feet. Moreover,if sloped rafters (or other framing systems) are used they may besupported by eave support assembly 110 and roof diaphragm 110 f may befastened to such sloped rafters (or the like) instead of directly toeave support assembly 110 members 110 a, 110 b, and 110 c, as depicted.

Longitudinal eave supports 110 c are arranged in a parallel relationshipwith respect to each other and with respect to longitudinal stiffeners110 b. Longitudinal eave supports 110 c provide a means to transfershear forces from roof diaphragm 110 f and are supported in acantilevered method by the distal ends of lateral eave supports 110 aproviding structural flexibility. Longitudinal eave supports 110 c arealso joined to and support eaves of a roof (not shown) for mobilestructure 100. A distance between longitudinal eave supports 110 c maybe between about six and about ten feet but not limited to this range ofdimensions. For example, this distance may vary in accordance with anexpected load placed on eave support assembly 110 and/or to accommodatea peaked roof having a desired slope.

Because rigid frames 104 can, in certain embodiments of mobile structure100, fully support a roof, stabilizing frames 106 or portions thereofmay optionally be omitted in those embodiments. Moreover, rigid frames104 may be positioned in locations other than those depicted. Forexample, in one alternative embodiment stabilizing frames 106 may beomitted and rigid frames 104 may be moved, along with primary levelingassemblies 112, to the spaces occupied by stabilizing frames 106. Inthis alternative embodiment, vertical supports 104 b of rigid frames 104(relocated to outer positions) extend at least partially past lateralsupports 104 c to restrain movement of horizontal roof supports 108 in alongitudinal direction.

In another alternative embodiment, rear rigid frame 104-1 and itscorresponding set of primary leveling assemblies 112 are omitted. Inthis embodiment, front rigid frame 104-1 and its corresponding set ofprimary leveling assemblies 112 may be moved toward the front or therear, as appropriate, to compensate for the omission of rear rigid frame104-1. Moreover, in a deployed configuration, this alternativeembodiment of mobile structure 100 may be configured to rest on wheelsof wheel-axle assembly 102 f in addition to primary and secondaryleveling assemblies 112 and 114.

In a further modification of the immediately foregoing alternativeembodiment, front rig id frame 104-1 has a structure similar tostabilizing frames 106. More specifically, vertical supports 104 b offront rigid frame 104-1 may extend past bottom chords 108 b ofhorizontal roof supports 108 and an additional lateral support may beincluded above lateral support 104 c. Accordingly, horizontal roofsupports 108 in this embodiment are segmented and face-mounted on eitherside of the modified front rigid frame 104-1, thus forming a pair oftrusses on each side of front rigid frame 104-1 (i.e., a total of fourtrusses).

In another alternative embodiment, a single beam, such as an I-beam or arectangular or square cross-section beam, is used on each lateral sideof mobile structure 100 as horizontal roof supports 108. A beam istypically heavier and stronger, all else being equal, than an open-webtruss and, therefore, use of beams for horizontal roof supports 108 maybe appropriate in (but not limited to) circumstances in which weightrestrictions are more liberal and/or in which larger external forces areexpected.

FIG. 3 depicts a cross-section perspective view of one of rigid frames104 of mobile structure 100 and its surrounding structural elements.Peripheral carriage longitudinal channels 102 b are supported bycantilever from transverse joists 102 c (hidden from view by floordiaphragm 102 a) over interior carriage longitudinal beams 102 j.Longitudinal stiffeners 102 k provide stability from overturning oftransverse joists 102 c. Interior carriage longitudinal beams 102 jsupport wheel-axle assembly 102 f, and are joined (e.g., via a rigidconnection) under floor diaphragm 102 a to outer sides of verticalsupports 104 b of rigid frames 104. Floor diaphragm 102 a, transversejoists 102 c, peripheral carriage longitudinal beams 102 b, andlongitudinal stiffeners 102 k work in conjunction to transfer floorloads back to rigid frames 104, which in turn transfer the floor loadsto a ground surface via primary leveling assemblies 112. Floor loads aretransferred to rigid frames 104 at least partially through fasteners(e.g., nails, bolts, or screws) that join floor diaphragm 102 a to a topside of lateral floor joists 104 a of rigid frames 104. Similarfasteners may also join floor diaphragm 102 a to lateral floor joists106 a of stabilizing frames 106 and to transverse joists 102 c ofcarriage assembly 102.

Horizontal roof supports 108, including tension and compression members108 a and top and bottom chords 108 b, are also visible in FIG. 3.Although tension and compression members 108 a appear to be floating anddisconnected from any adjoining structure, this appearance is anartifact due to the limitations of a cross-sectional view. As shown inFIG. 2, tension and compression members 108 a are actually formed intriangular patterns and span from one end of horizontal roof supports108 to the other.

As described above with respect to carriage assembly 102, any suitablematerials may be used to make the various parts of rigid frames 104,stabilizing frames 106, horizontal roof supports 108, eave supportassembly 110, and primary and secondary leveling assemblies 112 and 114.In addition, various shapes and configurations of materials may be usedfor the structural framing elements. For example, I-beams, L-beams,C-beams, hollow rectangular or square cross-section beams, solidrectangular or square cross-section beams, or any combination thereofmay be used for horizontally, vertically, and/or diagonally orientedsupports, beams, or joists. Moreover, parts may be joined by any jointtype appropriate for the materials being joined including, e.g., weldedjoints or mortise and tenon joints, and any suitable joint fasteners maybe used, such as bolts, nails, screws, rivets, adhesives, etc.

U.S. Provisional Patent Application No. 61/271,925, entitled“SUSTAINABLE, MOBILE, EXPANDABLE STRUCTURE,” filed Jul. 28, 2009,describes and depicts a finished mobile structure that uses thestructural elements of mobile structure 100 described above. Thedescription in the foregoing provisional application also describes indetail foldable wall panel assemblies that are joined to peripheralcarriage longitudinal channels 102 b and foldable roof panel assembliesthat are joined to fixed roof panels, which are in turn joined to eavesupport assembly 110. The foldable wall panel assemblies and foldableroof panel assemblies may be joined via hinged joints to structuralelements or to other elements mounted on the structural elementsdepicted in FIG. 2. In an expanded mode of mobile structure 100 thefoldable wall panel assemblies and foldable roof panel assemblies areunfolded or extended to create expansion sections on lateral sides ofmobile structure 100. However, embodiments of the present invention arenot limited to expandable mobile structures of the type described in theabove-referenced provisional application. For example, mobile structuresbuilt in accordance with the principles described above may havepermanently fixed wall and roof panels that do not expand or retractfrom a central body.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. Therefore, thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. Moreover, the scope of the inventionis indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A portable structure having sufficient internalstructural rigidity to eliminate load-bearing perimeter supportstructure, the portable structure comprising: first and second rigidframes, each of the first and second rigid frames including: at leasttwo mutually parallel vertical supports; and mutually parallel lateralroof and floor joist supports each extending perpendicularly between theat least two vertical supports; a carriage assembly, the carriageassembly supporting a floor diaphragm coupled thereto, the carriageassembly being rigidly coupled to the lateral floor joist supports ofeach of the first and second frames; at least two mutually parallelhorizontal roof supports supporting a roof diaphragm, the horizontalroof supports being substantially perpendicular with, and rigidlycoupled to, the lateral roof supports of the first and second rigidframes; and at least one set of leveling assemblies configured tosupport said portable structure when in a stationary mode, each of theat least one set of leveling assemblies configured to be inweight-bearing and in-line relationship with respect to one of thevertical supports of one of the first and second rigid frames, wherebywhenever the leveling assemblies are extended to and rigidly coupled tothe ground, substantially all lateral forces imposed on said portablestructure are transferred to the ground through the one of the first andsecond rigid frames.
 2. The portable structure of claim 1, wherein theleveling assemblies are retractable from their extended configurationwhen the portable structure is in a transport mode.
 3. The portablestructure of claim 1, further comprising an eave support assemblycoupled between the roof diaphragm and the horizontal roof supports, theeave support assembly being in a cantilevered relationship with thehorizontal roof supports.
 4. The portable structure of claim 1, whereinthe horizontal roof supports are in a cantilevered relationship with thefirst and second rigid frames.
 5. The portable structure of claim 3,wherein: said portable structure has two sides and two ends, thedistance between the sides being its width and the distance between theends being its length; and the first and second rigid frames beingsymmetrically oriented so that the first and second lateral supports ofthe rigid frames are substantially perpendicular to the sides, andsubstantially parallel to the ends of said portable structure, anddisposed in a space that is located inside of the length of saidportable structure.
 6. The portable structure of claim 5, wherein atleast the roof lateral supports of the first and second rigid frames donot extend the entire width of said portable structure, therebyproviding room, at least along the sides of said portable structure for,lateral extension structures supported by at least one of: the eaveassembly and the carriage assembly.
 7. The portable structure of claim5, further comprising: at least one stabilizing frame including: atleast two mutually parallel vertical stabilizing supports; and first andsecond mutually parallel lateral roof supports; and a lateral floorjoist support, wherein: the first and second lateral roof supports andthe lateral floor joist support extend perpendicularly between the atleast two vertical stabilizing supports; and the first lateral roofsupport is rigidly coupled to the horizontal roof supports, the secondlateral roof support is rigidly coupled to the eave support assembly,and the lateral floor joist support is rigidly coupled to the carriageassembly.
 8. The portable structure of claim 7, wherein the at least onestabilizing frame is disposed outside of a space between the first andsecond rigid frames, and disposed in substantially symmetricrelationship with respect to the first and second rigid frames.
 9. Theportable structure of claim 5, wherein the eave support assembly issupported by the first and second horizontal roof supports, the eavesupport assembly including: a first longitudinal eave support; a secondlongitudinal eave support substantially parallel to the firstlongitudinal eave support; and a plurality of lateral eave supports eachextending perpendicularly at least from the first longitudinal eavesupport to the second longitudinal eave support, the first and secondlongitudinal eave supports being separated from one another by adistance greater than a distance separating the first and secondvertical supports of at least one of the first and second rigid frames.10. The portable structure of claim 9, wherein each of the horizontalroof supports includes a truss, the truss comprising: a bottom chordrigidly coupled to the lateral roof supports of the first and secondrigid frames; a top chord disposed above and in parallel with the bottomchord, the top chord being rigidly coupled to the eave support assembly;and truss members disposed in triangular patterns between the top andbottom chords.
 11. The portable structure of claim 1, wherein thehorizontal roof supports are solid members.
 12. The portable structureof claim 1, wherein an extension distance of at least one of theleveling assemblies of the first set of leveling assemblies isautomatically adjustable.
 13. The portable structure of claim 1, whereinat least one of the leveling assemblies of the first set of levelingassemblies includes a base plate to distribute a load of the portablestructure over an area under the base plate.
 14. The portable structureof claim 1, wherein each of the vertical supports of the first rigidframe extends through the floor diaphragm and is directly coupled to acorresponding one of the leveling assemblies of the first set ofleveling assemblies.